Hi I had a question.
I'm having an issue with my car.
2003 mini cooper s r53.

Also I don't get a check engine light at all. It happens when at cold start and idle. I notice I have a hard start issue and then after driving for a while I notice at idle the car start hunting or chugging. I give the throttle a small blip and it's back to normal.

Parts replaced.<ecu that came with car was jcw but engine was replaced. So current engine is the reg r53 s from a <05 r52>

OK
Head job
15%pulley
Crank pulley
Belt
Both map sensors
Btv bypass
New jcw injectors
Cam,crank,and knock sensors
Charcoal canister and dmtl
Oil pump
Pcv
All gaskets
Flywheel and clutch (stage 2)
Fuel pump and sending unit
Purge valve
Had ecu flashed.
Both o2 sensors ,headers aswell.
The small little lines under the intake manifold look good not brittle at all.
I know it's more but can't remember off the top.



I notice when I did a pressure test I'm getting around 41 psi at idle not 42 or 43 psi I see others say they have. But the problem is that when I leave the pressure tester on for 20 or 30 mins the pressure only rises almost to 56 or 55psi sometimes.
And I see on the forums that allllllloooootttttt of people are dealing with this issue and still haven't fixed it. 😐

I noticed today when I went to get some gas that I heard a sort of fart noise when I removed the gas cap.
And lastly I've been doing some research and I see that the fuel tanks breather line has a fuel vapor separator which has a roll over valve inside of it. Has anyone ever heard of this valve or this issue.
Also my I heard that the return or feed lines can also be what going on.
😒 <at my wits end>
here are some pics of that vapor separator and the roll over valve.
J

 

So, for clarification - both the engine and ECU are non-JCW? You're running JCW injectors but if the ECU doesn't have a JCW tune then your fuel trims will be all over the place and could cause issues.

When you say the fuel pressure rises to 55-56psi over time, is this with the engine running or after it is shut off?

Have you scanned for error codes with a BMW/MINI specific code reader (not a generic OBD reader)?

It should be easy enough to pull off the vent line to see if the roll-over valve is stuck/clogged, but I've never heard of this being an issue.

 

Mrbean thank for your reply. Well the car is originally a jcw but the current motor is from a 2006 r52s. So the injectors should be firing good because the ecu is a jcw.

The fuel pressure rises to 55 or 56 psi when I shut the engine off.

Oh another piece of info is that I had the head port and polished by install.

Yes I got it scanned from a friend who had an autologic and the only thing coming up is a code for the cruise control. But nothing even when its hunting or chugging at idle.
Anyway
Going to do a compression test right now to see what my readings are. Thanks again.